Reconsidering Speck

Posted Aug 9, 2018 18:04 UTC (Thu) by Cyberax (✭ supporter ✭, #52523)
In reply to: Reconsidering Speck by felixfix
Parent article: Reconsidering Speck

Have you _checked_ the source code? There are no hidden parameters in Speck. It's dead simple.

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Reconsidering Speck

Posted Aug 9, 2018 18:54 UTC (Thu) by felixfix (subscriber, #242) [Link] (2 responses)

Have you checked the source code for the XOR cypher? It's even simpler.

Oh ho! you say, I know that trick. It's not a real cypher!

And there's your answer. Not all backdoors are secret hard-coded passwords.

Reconsidering Speck

Posted Aug 9, 2018 19:00 UTC (Thu) by Cyberax (✭ supporter ✭, #52523) [Link] (1 responses)

XOR with a one-time pad is a good cipher. So nope.

Reconsidering Speck

Posted Aug 9, 2018 23:02 UTC (Thu) by simcop2387 (subscriber, #101710) [Link]

XOR with a one time pad is only as good as the pad. If it has patterns (bit 12 is never set) or was generated with a backdoored RNG, then it's no longer a good cipher.

The argument here is that because the rationale hasn't been provided (maybe even if it had been), we can't know if the NSA has a way to know something like, if bits 12 and 13 of the key are set to 01 then bits 0-7 of the key only end up adding 2 bits of entropy to the result (obviously an overly simplified example).

The attacks on the rationale that has been provided are better covered in other comments, but it basically seems to boil down to "There's a lot of unanswered questions we have about this, that everything else we use has answered, why won't you answer them?"